What does the lonely root number three mean?

The root number three is used to describe a person's loneliness. It was originally a foreign love poem, which was well known by Zhan Bo in the TV series ipartment.

I will always be the root of loneliness.

How wonderful the third number itself is,

My three,

Why are you hiding under that ugly root number?

How I wish I was a 9,

Because nine only needs a small operation,

Can get rid of this cruel fate.